1. Field of the Invention
The present invention relates to a paper processing apparatus that processes paper (sheets) discharged from an image forming apparatus, such as a printer or a copying machine, and in particular relates to a paper processing apparatus including a paper cutting mechanism.
2. Description of the Related Art
Many proposals have conventionally been made in regard to paper processing apparatus in which recorded paper (sheets) that is discharged from an image forming apparatus, such as a printer or a copying machine, is retrieved as a bound book. For instance, paper processing apparatus have been proposed in which paper that is discharged from an image forming apparatus and stacked is bound in a central portion thereof, the paper is bound at the bound position and folded in two, the folded paper is pressed, an end thereof is cut, and the paper is retrieved as a bound book.
FIG. 6 is view for describing a conventional paper processing apparatus. A paper processing apparatus 201 that is connected to an image forming apparatus 200 receives, at input rollers 202, paper that has been discharged from ejection rollers 230 of the image forming apparatus 200 and conveys, with conveyance rollers 203, the paper within a conveyance path 220. Using a turn roller 204 and a switching detent 205, a paper stack is accommodated at a stacker 206 after the paper passes along a U-turn conveyance path where the conveyance path is largely curved. The stacker 206 extends diagonally downward, from an upper portion of a surface (opposite surface side; left-side surface in FIG. 6) that is opposite from a paper conveyance path surface side (right-side surface in FIG. 6) including the input rollers 202 toward the paper conveyance path surface side (right-side surface in FIG. 6). The width-direction size of the accommodated paper stack is positioned by a positioning stopper 208 that is moved up and down by the rotation of a belt 207, and the center portion of the accommodated paper stack is bound by a stapler 210. Thereafter, the positioning stopper 208 moves upward, so that the center portion reaches a position of a folding blade 211.
In a folding operation, the folding blade 211 proceeds diagonally forward, from above to below, by turning on a solenoid 216, and the folding blade 211 presses the paper stack against a paper stack discharge port 209 and initiates folding. The cut paper stack is fed to pre-press rollers 212 and further conveyed downstream. Thereafter, the folding is intensified by press rollers 214, and the paper stack is conveyed to a cutting position of a slidable cutting device 213 and stopped. A cutting blade of the slidable cutting device 213 is moved from up to down, and an end of the folded paper stack is cut by a guillotine format by the cutting blade and a fixed blade. Thereafter, the cut paper stack is stacked in a discharge tray 215 as a center-bound book.
In these mechanisms, there is technology in which the cutting position is determined while the center-bound book that is to be cut is held by the press rollers 214, and the pointed cutting blade of the slidable cutting device 213 is lowered to cut the center-bound book, whereby the end of the center-bound book is precisely and cleanly cut (e.g., see JP-A-2000-143081 (pp. 5-6, FIG. 1)). There is also technology in which the paper ends are cut by paper cutting means in a state in which the bound folded paper straddles both paper cutting means, such as the slidable cutting device 213, and paper stacking means, such as the discharge tray 215, whereby the dispositional area of the device can be made smaller by only the dimension at which the paper sticks out (e.g., see JP-A-2000-103567 (pp. 3-4, FIG. 1 )).
In recent years, there has been a strong demand to miniaturize and make apparatus compact, and also to conserve the energy of apparatus from an ecological standpoint. This trend is the same with respect to post-processing apparatus of image processing apparatus. When one looks at the above-mentioned technology of JP-A-2000-143081 and JP-A-2000-103567, a slidable cutting device that employs the guillotine format is used as the cutting device, and this slidable cutting device is superior in that its cutting action is fast. However, because the guillotine format is employed, it is necessary for the stroke of the cutting blade to be large, which results in the overall apparatus becoming large. It also becomes necessary to dispose the cutting blade across the entire width of the paper, which results in an unavoidable increase in the cost of the cutting blade. Moreover, it becomes necessary for the load to be concentrated in order to cut the paper instantaneously and for the driving current and the starting current to be extremely large, so that improvements are demanded from an ecological standpoint. Furthermore, there has not been much freedom with respect to places where the cutting device can be disposed because the cutting device itself becomes larger (e.g., the discharge port must be disposed downstream of the device), and it has been difficult to provide a paper processing apparatus that is easy to use from the standpoint of the user.